Hawkins electrical guide ... : questions, answers & illustrations : a progressive course of study for engineers, electricians, students and those desiring to acquire a working knowledge of electricity and its applications ; a practical treatise (1914)
Hawkins, N. (Nehemiah), 1833-1928 · New York : T. Audel & Co. · leaf 552
ELECTRIC RAILWAYS 2,643 Electric Interlocking.—When a switch lever in a tower ismanually moved from normal to reverse, the locking betweenit and the signal lever controlling the governing movementsof the signal over the switch reversed is instantly released,but when electric power is used for… … F;g. 3,733.—Interlocking relay for alternating current. The contact springs are glass enclosed.Each armature may be equipped with as many as three extra front and back contacts inaddition to interlocking contacts, of which there may be as many as four. It is an im-proved type of polyphase relay.…
Electrical engineering
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